{"api_version":"1","generated_at":"2026-10-27T07:13:45+00:00","cve":"CVE-2026-56386","urls":{"html":"https://cve.report/CVE-2026-56386","api":"https://cve.report/api/cve/CVE-2026-56386.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-56386","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-56386"},"summary":{"title":"Apache bRPC: Integer Underflow and Out-of-Bounds Read in HTTP/2 DATA Frame Parser","description":"Integer underflow and out-of-bounds read in the HTTP/2 server DATA frame parser in Apache bRPC allows an unauthenticated remote attacker to cause denial of service by sending a malformed DATA frame with the PADDED flag set and a zero-length payload.\n\nRoot Cause:\nThe HTTP/2 DATA frame handler computed the fragment size from the attacker-controlled payload length and, when the PADDED flag was present, decremented the fragment size before ensuring that the frame contained the mandatory pad length byte. A zero-length padded DATA frame could therefore underflow the unsigned fragment size and read the pad length byte past the end of the frame buffer.\n\nAffected Scenarios:\nApache bRPC servers that accept HTTP/2 traffic are affected when a remote client can send crafted HTTP/2 frames to the server. HTTP/2 may be reached through cleartext h2c detection on an HTTP port or through TLS ALPN negotiation.\n\nHow to Fix:\n(Choose one of the following options)\n1. Upgrade Apache bRPC to version 1.18.0, which fixes this issue.\n2. Apply this patch:  https://github.com/apache/brpc/pull/3325 \n\nNote:\nThe fix validates that a padded DATA frame has enough payload bytes for the pad length field before decrementing the fragment size or reading the pad length byte. 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A zero-length padded DATA frame could therefore underflow the unsigned fragment size and read the pad length byte past the end of the frame buffer.<br><br>Affected Scenarios:<br>Apache bRPC servers that accept HTTP/2 traffic are affected when a remote client can send crafted HTTP/2 frames to the server. HTTP/2 may be reached through cleartext h2c detection on an HTTP port or through TLS ALPN negotiation.<br><br>How to Fix:<br>(Choose one of the following options)<br>1. Upgrade Apache bRPC to version 1.18.0, which fixes this issue.<br>2. Apply this patch: <a target=\"_blank\" rel=\"nofollow\" href=\"https://github.com/apache/brpc/pull/3325\">https://github.com/apache/brpc/pull/3325</a><br><br>Note:<br>The fix validates that a padded DATA frame has enough payload bytes for the pad length field before decrementing the fragment size or reading the pad length byte. 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HTTP/2 may be reached through cleartext h2c detection on an HTTP port or through TLS ALPN negotiation.\n\nHow to Fix:\n(Choose one of the following options)\n1. Upgrade Apache bRPC to version 1.18.0, which fixes this issue.\n2. Apply this patch:  https://github.com/apache/brpc/pull/3325 \n\nNote:\nThe fix validates that a padded DATA frame has enough payload bytes for the pad length field before decrementing the fragment size or reading the pad length byte. 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A zero-length padded DATA frame could therefore underflow the unsigned fragment size and read the pad length byte past the end of the frame buffer.\n\nAffected Scenarios:\nApache bRPC servers that accept HTTP/2 traffic are affected when a remote client can send crafted HTTP/2 frames to the server. HTTP/2 may be reached through cleartext h2c detection on an HTTP port or through TLS ALPN negotiation.\n\nHow to Fix:\n(Choose one of the following options)\n1. Upgrade Apache bRPC to version 1.18.0, which fixes this issue.\n2. Apply this patch:  https://github.com/apache/brpc/pull/3325 \n\nNote:\nThe fix validates that a padded DATA frame has enough payload bytes for the pad length field before decrementing the fragment size or reading the pad length byte. Malformed zero-length padded DATA frames are rejected with HTTP/2 FRAME_SIZE_ERROR.","Type":"Description","Title":"Apache bRPC: Integer Underflow and Out-of-Bounds Read in HTTP/2 "}]}}}